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2009 Forester XT Ltd 4 speed auto
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Discussion Starter #1
Just had Takata airbag recall handled at dealer....they of course gave my '11 Ltd Fossie the once over and found some items recommended for repair
My question ... are the low beam bulbs better as Halogen bulbs or are the newer LED bulbs better? And will the LED bulbs mount in same bracket and will it need any modifications?
 

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2018 Forester XT Limited CVT
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482 Posts
Oh, now I like this! Looks like Diode Dynamics AND Sealight both perform WORSE.
The DD is worse in the "Range" measurement but is close in the other two (better in the "Downroad"). We are talking compared to H11, not compared to the better Philips XtremeVision which I believe is an upgrade over stock. Also remember that the sensitivity to light of human eyes is not linear. For example to increase one stop of exposure you have to double the amount of light.

Sealight emitters are improperly located, so I would omit them as an option. I don't know about DD.
 

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I took another look at the tests, and they were run at 12.8 volts.

531802


All the halogen results should be multiplied by 1.1 or 1.2 to get realistic numbers, since a car's alternator doesn't output just 12.8 volts (unless it's broken). LED on the other hand is not responsive to changes in voltage.
 

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2018 Forester XT Limited CVT
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All the halogen results should be multiplied by 1.1 or 1.2 to get realistic numbers, since a car's alternator doesn't output just 12.8 volts (unless it's broken). LED on the other hand is not responsive to changes in voltage.
Incandescent intensity depends on power output not voltage. P = IV = (V^2)/R = (I^2)R and (for an incandescent filament) R is dependent on temperature, which is dependent on power. They size the filament for the power they want at the voltage (and current capacity) of the system. R starts out at zero when the bulb is cold and then increases. It's difficult to know what voltage to test at because alternator output depends on sensor input and firmware and desired charge algorithm and is changing as the engine runs (in the old days it was a constant voltage, or two). And given the pursuit of economy the firmware will cut out as much load as it can. But yes 12.8 V is like the engine is off, and a lot of people need to use the headlights when the engine is running as well.

To try to interpolate intensity going from 12.8 V to an alternator voltage isn't going to be linear due to the physics (equations above). You can turn the knobs to get the power level you want which will give you a corresponding change in intensity, but increasing the light output by 10% doesn't mean you perceive things are 10% brighter due to the response curve of your eyes to the amount of light. One photographic stop is a doubling of the amount of light, and people deal with 1/2 stops and 1/3 stops. If you're not a photographer you may be able to find a visual comparison of stops on the Internet somewhere. So if you go from X lumens to (1.1)X that's not the same as 1.1 stops.

Again due to the pursuit of economy, incandescent lights are going to be deprecated over time. All the bulbs discussed here are just retrofits anyway and new units will have LEDs with appropriate collimating devices.

LED output is responsive to changes in current and LEDs are kept at the proper forward voltage and current required, by their power supplies. So yeah they are sort of responsive in that if you increase the voltage the power supplies will draw less current, in keeping the electrical conditions at the emitters as desired. But no the LED system (power supply and emitter) are not passive elemental devices like an incandescent resistive element. They regulate themselves and are not a primitive like a filament. I don't mean primitive like caveman, I mean primitive like atomic, elemental, etc.
 

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1999 Forester S
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Sealight emitters are improperly located, so I would omit them as an option. I don't know about DD.
LED bulbs designed to plug into a halogen housing physically cannot locate an LED array is such a way as to properly replicate an incandescent filament, so Sealight or DD, it doesn't really matter.

Yes, there is LED bulb geometry that makes the output closer to halogen bulbs, but even then they're a universal geometry across all headlamp applications.
 

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2018 Forester XT Limited CVT
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LED bulbs designed to plug into a halogen housing physically cannot locate an LED array is such a way as to properly replicate an incandescent filament, so Sealight or DD, it doesn't really matter.

Yes, there is LED bulb geometry that makes the output closer to halogen bulbs, but even then they're a universal geometry across all headlamp applications.
Manufacturers have the capability to locate the emitters wherever needed. Sealight is off, I don't know about DD. If I were in the market, I'd look at the DD bulbs and see where the emitters were. If they were in the right place I would install them, and they'd be good enough, at least as close as a sloppy Sylvania if not better, but the problem for me would be that they have cooling fans. How do you know whether or not the fan needs replacement or attention? What if you get road debris in the fan? I'd probably wait for an option without a fan.

Stay safe during the pandemic.
 

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Sahuarita, Arizona USA 2018 Forester Limited
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Also, do the DD's (or any LED for that matter) burn warm enough to keep the headlight lens clear of snow and ice? Don't know, just asking.
 

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2018 Forester XT Limited CVT
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Also, do the DD's (or any LED for that matter) burn warm enough to keep the headlight lens clear of snow and ice? Don't know, just asking.
The LED heat conducts out and dissipation is from the heatsink. I guess it'd be smart to put the heatsink out front, but they don't. This would be a concern for factory LEDs as well as retrofits. In my experience incandescents don't keep the lens clear of snow and ice either.
 
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